The present invention relates to optical communication techniques. More particularly, the present invention provides an optical dispersion compensator integrated in a silicon photonics system.
Over the last few decades, the use of communication networks exploded. In the early days Internet, popular applications were limited to emails, bulletin board, and mostly informational and text-based web page surfing, and the amount of data transferred was usually relatively small. Today, Internet and mobile applications demand a huge amount of bandwidth for transferring photo, video, music, and other multimedia files. For example, a social network like Facebook processes more than 500 TB of data daily. With such high demands on data and data transfer, existing data communication systems need to be improved to address these needs.
Progress in computer technology (and the continuation of Moore's Law) is becoming increasingly dependent on faster data transfer between and within microchips. Optical interconnects may provide a way forward, and silicon photonics may prove particularly useful, once integrated on the standard silicon chips. 40-Gbit/s and then 100-Gbit/s data rates WDM optical transmission over existing single-mode fiber is a target for the next generation of fiber-optic communication networks. The big hangup so far has been the fiber impairments like chromatic dispersion that are slowing the communication signal down. Chromatic dispersion is a result of the dependence of the refractive index on the wavelength. Different frequency components of the light-wave experience different phase delays due to the refractive index change. The phase difference causes distortion on the signal. Especially for high-speed communication beyond 10 Gbits/s, distortion and attenuation of the optical signals take their toll.
In order to compensate the dispersion in the fiber, traditional method is to use a discrete dispersion compensator formed on Silica-based Planar Lightwave Circuit (PLC). Such traditional device has very large dimension in centimeter range and is not suitable for small package silicon photonics modules. Therefore, an improved dispersion compensator that is compatible with a silicon photonics system is desired.